Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
abudawud:1972ʿAbdullāh b. Muḥammad al-Zuhrī > Sufyān > Misʿar > And Barah > Saʾalt Ibn ʿUmar Matá Armī al-Jimār > Idhā Ramá Imāmuk Fārm Faʾaʿadt ʿAlayh al-Masʾalah

I asked Ibn 'Umar: When should I throw pebbles at the jamrah? He replied: When your imam (leader at Hajj) throws pebbles, at that time you should throw them. I repeated the question to him. Thereupon he said: We used to wait for the time when the sun passes the meridian. When the sun declined, we threw the pebbles.  

أبو داود:١٩٧٢حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ الزُّهْرِيُّ حَدَّثَنَا سُفْيَانُ عَنْ مِسْعَرٍ عَنْ وَبَرَةَ قَالَ سَأَلْتُ ابْنَ عُمَرَ مَتَى أَرْمِي الْجِمَارَ قَالَ

إِذَا رَمَى إِمَامُكَ فَارْمِ فَأَعَدْتُ عَلَيْهِ الْمَسْأَلَةَ فَقَالَ كُنَّا نَتَحَيَّنُ زَوَالَ الشَّمْسِ فَإِذَا زَالَتِ الشَّمْسُ رَمَيْنَا  


See similar narrations below:

Collected by Bukhārī
bukhari:1746Abū Nuʿaym > Misʿar > And Barah > Saʾalt Ibn ʿUmar Matá Armī al-Jimār > Idhā Ramá Imāmuk Fārmih Faʾaʿadt ʿAlayh al-Masʾalah

I asked Ibn ʿUmar, "When should I do the Rami of the Jimar?" He replied, "When your leader does that." I asked him again the same question. He replied, "We used to wait till the sun declined and then we would do the Rami (i.e. on the 11th and 12th of Dhul-Hijja)."  

البخاري:١٧٤٦حَدَّثَنَا أَبُو نُعَيْمٍ حَدَّثَنَا مِسْعَرٌ عَنْ وَبَرَةَ قَالَ سَأَلْتُ ابْنَ عُمَرَ ؓ مَتَى أَرْمِي الْجِمَارَ قَالَ

إِذَا رَمَى إِمَامُكَ فَارْمِهْ فَأَعَدْتُ عَلَيْهِ الْمَسْأَلَةَ قَالَ كُنَّا نَتَحَيَّنُ فَإِذَا زَالَتِ الشَّمْسُ رَمَيْنَا